The following list explains some of the abbreviations used in this specification:    AC admission control    AMR adaptive multi rate    BS base station    BTS base transceiver station    CDMA code division multiple access    C/I carrier to interference ratio    FER frame error rate    GSM general system for mobile communications    LC load control    MAC medium access control    RM radio resource manager    RRC radio resource control    RRM radio resource management    RNC radio network controller    SHO soft handover    TC transcoder    TF transport format    TFS transport format set    UE user equipment    UMTS universal mobile telecommunication system    UTRAN UMTS terrestrial radio access network    WCDMA wideband CDMA
The AMR concept provides a multi rate capability for connections between a mobile station (MS) and a network. The mobile station can also be referred to as ‘User Equipment’ (UE). The AMR speech codec has 8 different bit rates (4.75 kbps. 12.2 kbps) for speech coding. A higher bit rate provides better speech quality but gives lower capacity and coverage. In GSM the AMR control is a link level control function, controlled by BTS. For control of downlink direction, the mobile station (MS) reports observed C/I to BTS. For control of uplink direction, the BTS measures C/I.
The present specifications of the WCDMA system leave room for improvement of the usage of the AMR concept. The present specifications do not describe adequate methods to optimize transmission control with the AMR concept.